Context Navigation

Section_6

Timestamp:: Oct 9, 2013, 1:52:22 PM (11 years ago)
Author:: Michele Selvaggi
Comment:: --

Legend:

: Unmodified
: Added
: Removed
: Modified

Private/RefereeComments/Section_6

-              v12
+              v13
 >>> The authors disagree with this comment. The reasons are:
+>>>- the resolutions in the Delphes CMS and ATLAS cards are directly taken from CMS and ATLAS.
+>>>- the resolutions from CMS and ATLAS are taken directly from the cited papers, and it would be redundant to quote there here.
+>>>- the only possible difference is in the calorimeters granularity. Both the CMS and ATLAS configurations in Delphes use the granularity of the HCAL detector. As said in the calorimeter section, the ECAL granularity is exactly the same as the HCAL >>> granularity in Delphes. This comment has now been added in the "jet and met"validation sub-section".  A table with the actual HCAL granularity of the LHC experiments (already public in the relevant technical design reports of CMS and ATLAS) >>> would be of poor interest to the reader and redundant.
+>>>- the resolutions in the Delphes CMS and ATLAS cards are taken directly from the cited papers, and it would be redundant to quote them here.
+>>>- the only possible difference is in the calorimeters granularity. Both the CMS and ATLAS configurations in Delphes use the granularity of the HCAL detector. As said in the calorimeter section, the ECAL granularity is exactly the same as the HCAL >>> granularity in Delphes. This comment has now been added.  A table with the actual HCAL granularity of the LHC experiments (already public in the relevant technical design reports of CMS and ATLAS) >>> would be of poor interest to the reader and redundant.
 PAGE 13
 …
  * It is not clear what the grey bands are in this plot. Shouldn’t they be removed? In CMS, they are supposed to cover differences between the simulation and the data in CMS, not the difference between Delphes and CMS. This comment is valid for all plots. Strangely enough, the ATLAS fred band width is way smaller than that for CMS. Does it represent the same thing ?
 >>> the grey bands mean indeed different things in the left and right plots. The caption has been extended in order to explain the details required by the referee.
+>>> the grey bands mean different things in the left and right plots. The caption has been extended in order to explain the details required by the referee.
  * For all plots, it is important to have the statistical uncertainty bars indicated, or to state that they are covered by the size of the markers. In the latter case, an explanation is needed for the apparent scatter of the DELPHES points, and to compare this scatter with the input resolution function.
 >>> The apparent scatter is just due to the fact the the parametrisation of the resolution is binned, and has been chosen to match approximately that of CMS and ATLAS. The choice was made to adopt round values which may result in the apparent scatter. As these plots are just an illustration of a parametrisation which is correct by construction, we believe that no further explanation is needed.
 …
 >>> This plot has been re-done. The HCAL calorimeter resolution has been set to the actual CMS resolution, and the energy-flow implementation is as explained in Section 2.3.
 >>> As a result we have a perfect agreement at all medium and high pt values. At low pt there is a discrepancy for 20<pt<30 which is not understood. However we believe this discrepancy to have very low impact on physics analyses, that most often
 >>> consider jets with pt > 30. The small discrepancy observed in the 30 > pt > 40 GeV bin is ~1% in resolution. This comments have been added in the text.
+>>> consider jets with pt > 30. The small discrepancy observed in the 30 > pt > 40 GeV bin is ~1% in resolution. These comments have been added in the text.
 Once the effects are understood, it would be important to fix the imple-
 …
 >>> addressed. However, the referee, as well as the LHC experiments, should be aware that any study performed with Delphes should be understood as preliminary. A Delphes based study should be perfomed after a pure parton-level and before
 >>> a geant based fast or  full-simulation study. As a result, the authors are perfectly happy with an agreement with a few percents discrepancy in the physics object resolutions.
+>>> a geant based fast or full-simulation study. As a result, the authors are perfectly happy with an agreement with a few percents discrepancy in the physics object resolutions.
 == Section 6.3 ==
 …
 >>> We don't want to create to much imbalance between CMS and ATLAS (the only exception is electrons, but we did not find the relevant plot for ATLAS),
 >>> so we have decided to produce a real MET validation plot for CMS and and the fake validation for ATLAS. This choice was simply driven by the fact that the real MET
+>>> so we have decided to produce a real MET validation plot for CMS and the fake validation for ATLAS. This choice was simply driven by the fact that the real MET
 >>> validation plot was not found in the ATLAS. In addition, pile-up mitigation for MET has not been addressed in this note, since it is not done.
 >>> As a matter of fact PU mitigation on the MET relies on complex multi-variate algorithms
 …
 >>> to fine-tune them. The purpose was precisely to show the opposite: without particular fine-tuning
 >>> Delphes gives very reasonable agreement with the CMS analysis. We insist that a 20% difference
+>>> is an acceptable difference especially, if obtained with nominal b-tagging efficiency and naive jet energy energy scale corrections.
+>>> Very often results (rates, efficiencies) obtained with full geant based simulation give larger discrepancies than 20% with respect to data.
+>>> As a side comment, the effiencieny was re-computed after the change in the energy-flow algorithm and the result was found to be the same.
+>>> is an acceptable difference since very often results (rates, efficiencies) obtained with full geant based simulation give larger discrepancies than 20% with respect to data.
+>>> As a side comment, the efficiency was re-computed after the change in the energy-flow algorithm and the result was found to be the same.
 Par 2:
 …
 >>> the Delphes distributions are normalized to the total number of events in CMS (to account for the 20% in the selection efficiency).
 >>> since the total number of permutation is proportional to the event yield.
+>>> The total number of permutation is proportional to the event yield.
 >>> The purpose of this example is indeed to show, as Table 1 illustrates, that we get the correct fraction of each permutation category in Delphes.
 …
 comparison ?
 >>> These cuts a probably similar to a VBF analysis performed in ATLAS or CMS. However, the goal here is not to compare to any existing analysis,
+>>> These cuts a probably similar in any VBF analysis performed in ATLAS or CMS. However, the goal here is not to compare to any existing analysis,
 >>> but rather to give a simple example of utilisation of Delphes.
 …
 pile-up produced by LHC in 2012.
 >>> "high pile-up scenarios" has replaced by "extreme pile-up scenarios", which is we actually meant.
+>>> "high pile-up scenarios" has been replaced by "extreme pile-up scenarios", which is we actually meant.
 >>> To our knowledge there is no evidence that fast-simulation can cope to >100 simultaneous interactions environments, simply since these did not occur in any hadron collider yet.